Sewing machine



Dec. 9, 1947. N& v. CHRISTENSEN sswme MACH-INE- Filed Jan. 18, 1945 AT T 0511753 Patented Dec. 9, 1947 SEWING MACHINE Norman V. Christensen, Chicago, Ill., assignor to Union Special Machine Company, Chicago, Ill., a corporation of Illinois Application January 18, 1945, Serial No. 573,341

4 Claims.

This invention relates to an improved lockstitch sewing machine construction in which a fan is provided in association with a rotary hook for the purpose of cooling the latter and keeping it free of lint and dirt.

In lockstitch machines of the type to which the present invention is particularly applicable the rotary hook is of the 2 to 1 type and is given two revolutions for each reciprocation of the needle bar or for each stitch forming operation. Thus, when the machine is operated at a speed to produce 5,000 stitches per minute, as is now commonly done, the hook will revolve at a speed of 10,000 R. P. M. At such speeds of relative movement between the rib and raceway, or other cooperating surfaces, of the rotary and stationary components of the hook there is a serious tendency toward overheating. This may result in binding of the parts and permanent injury to the hook, and, in any event, causes deterioration of the lubricant for the hook raceway with likelihood of more serious difiiculty. The accumulation of lint or dirt, such as filler particles, on the hook contributes greatly to the danger of overheating. It also interferes .with the free movement of the needle thread loop around the bobbin case of the hook.

Siuggestions have heretofore been made of mounting a fan member or other ventilating means directly on the rotary component of a rotary hook for cleaning and cooling the same. These suggestions have, however, not proved entirely satisfactory and have been subject to various objections.

It has been a primary object of the present invention to provide a simple'but particularly desirable and eifective arrangement for blowing a steady stream of cooling and cleaning air against the back or bottom of a hook so long as it is in operation.

A further object has been to provide a hook cooling and cleaning arrangement of the character indicated which is free from interference with Or complication of the normal operation of the hook and which does not require modification of the hook structure.

Toward the foregoing ends the invention involves the provision of a simple type of fan, of substantially the same diameter as the hook, in close proximity to the hook but yet independent of the hook. The independent mounting of the fan, in the manner contemplated, has several distinct advantages. It enables removal and replacement of the hook without disturbing the fan. It also enables the interchangeable useof diiferent types of hooks in the same sewing ma;

rangement of the hook; cooling and cleaning fan in such relation to a portion of the frame of the machine that the most efiective use will be made of the air blown by the fan. This arrangement is such as to direct the entire stream against the back of the hook and around its periphery. As an extra, advantageous feature of this arrangement provision is made for drawing the air to the fan along such paths as to efiect cooling of other. parts of the construction, such as the bearing for the hook shaft and the eccentric which drives the feed rocker.

Other objects, features, and advantages of the invention will appear from the detailed description of an illustrative form of the same which will now be given in conjunction with the accompanying drawings, in which:

Figure I is a view, partly in front elevation and partly in longitudinal vertical section, of a portion of the needle head and the cooperating portion of the base of a sewing machine embodying the invention; I

Figure II is a detail view showing one form of fan which may be employed in accordance with the invention;

Figure III is a similar detail view of a modified form of fan; and

Figure IV is a view of the fan of Figure III as seen from the top.

Referring now to the drawings, the invention has been illustrated as applied to a machine of the general type disclosed in the Christensen et a1. Patent N 2,113,572, granted April 12, 1938, or of the modified form disclosed in the application of John G. Attwood, Serial No. 473,804, filed January 28, 1943. It will be understood, however, that the invention is capable of application to machines of other types.

As shown, the machine embodies a needle head in in which a needle bar ll carrying a needle I2 is mounted for vertical reciprocation. A presser bar [3 carrying a presser foot 14 is also mounted for vertical movement within the needle head and is normally urged downwardly, in conventional manner, by a suitable spring (not shown). Cooperating with the needle in stitch formation including such 3 is a, rotary hook, designated generally by the reference numeral I5, this hook being arranged to cooperate with a loop of the needle thread I6 as the latter is formed beneath the work sup porting surface I! of the base [8 at the beginning of the upstroke of the needle.

The rotary hook includes a stationary component l9 which serves as a retaineror holder for the bobbin carrying the under thread. This stationary component has a rib |9a which is in bearing engagement with a groove or raceway (not shown) in a rotary component 20 of the'hook. Since the hook may be of any suitable, known construction, it is not disclosed 'in detail herein. In the form illustrated in Figure I, the "rotary component is provided with a hub portion 2| by which it is attached in fixed relationythrough the use of the set screws 22, to a shaft 23. -If desired, the hook may be of the type illustrated'iii the above mentioned Attwood application, in

which no cylindrical hub portion is provided. Shaft 23 is mounted in a bea'ringsleeve -24 carried'by the frame 88 and is arranged to be rotated, through gearing 25, at an angular speed which is double that ofthe main shaft of the machine. 1 type, the rotary component being given two revolutions for each reciprocation of the needle bar, Since the driving connections froznthernain shaft of the sewing machine for reciprocating the needle bar and rotating the'rotarycompon'ent of the hook, and for also performing other functions such as the operation of the usual feed dog, may be of any suitable, known construction, these are not shown in the present caseand need not be further described. For further details as to their possible construction and'arrangement, reference may be had tothe Christensen et aL'patent and the Attwood application above mentioned.

Between the hub portion of the rotary component of the hook and the end of thebearing sleeve 24, there is secured to the shaft 23 a fan member 26. This, as illustrated in FiguresIand II, may suitably be ofvery simple construction and ma involvemerely a hub 21 and a pair of diametrically opposed vanes or blades23, 'These vanesmay suitably beflat and disposed at'an angle of abOu'tGO to the'axis'of shaft 2'3,-as shown, or they'may be of any other-suitable co'nfiguration and arrangementadaptedto produce a current of air moving toward the left inFigure I as the'shaft 23 is rotated. In lieu of a two bladed fan; such' as illustrated inFigure II, a three bladed member, as illustrated inFigur'e III, may be employed. This may, likewise, comprise simply a hub 21a having a series of symmetrically arranged vanes or blades 28a, each preferablyilat and disposed at an angle toth-eaxis. It will be understood, moreoventhat a fan member having a greater numberof bl'adesor vanes maybe employed, if desired, and the vanes may, regardless f their numberjbe of any'suitable configuration and arrangement adapted toprovide the desired movement of'air. Thet'wo fan members illustrated in Figures II and III, however, are exceedingly simple and sturdy in construction and are very eifectiv'e forthe desired purposes. The fan 'member of selected form, maybe secured "to the shaft '23'by means'ofset screws 29. As-showh in Figure I, it-is positioned closely adjacent to the end ofthe bearing sleeve 24 and may suitablytake the place "ofthe -thrust collar shown in the Christensen et-alipatentorin the Attwood application, abovementioned.

To increase the efficiency of the i fan rneiriber,

In other words, the hook is of the 2 to it is preferably mounted in a pocket 30 formed in the frame at the end of the bearing sleeve 24. A flange 3| extending longitudinally of the base from a downwardly extending wall or projection 32 of the frame, which wall supports the end of the bearing sleeve 24, may form the pocket 30 in conjunction with a portion of the work supporting-top of thebase. Preferably, also, the wall or projection 32 is provided with a series of holes or passages 33 which serve as air intake openings for the fan. These passages, communicatin'g with a recess 34 in the frame beneath the work support, cause the fan to draw air along "the bearing sleeve "24'and around the other de- *vic"eswithinthe recess 34, including an eccentric ohtlfdmainshaftin the base which cooperates with a strap :35 forming part of the feed dog operating mechanism, By virtue of the form of the pocket 30, the air impelled by the fan will be directed in a confined, cylindrical stream against the back or base of the rotary component 20 of the hook. A portion of this stream of air will pass through the openings 36 in the base of the rotar y component and will flow around the stationary component l9 to keep the latter, and the bearing surfaces between the two components of the hook, clean and'free of lint and filler substances. Another portion of the stream of air will flow around the outer periphery of the rotary component. Thus, in addition to keeping the hook clean, a definite cooling action i provided 'and this not only prevents injury to the hook,

due to overheating, but it serves to prolong the life and increase the usefulness of the lubricant applied to the bearing surfaces of the two components of the hook.

Due to the mounting of the fan member independently of the hook itself, and due also to the location of the fan adjacent the end of the bearing sleeve 24, it will not impart any substantial vibrational force to the hook or to the hook shaft, even when the latter is revolved at speeds in excess of 10,000 R. P. M, The addition of extra weight to the rotary component of the hook at some distance from the closest bearing support, which occurs in certain prior art constructions, has been avoided. Moreover, there is nothing in the new construction to throw the hook out of balance. The symmetrical arrangement of the impeller elements of the fan serves to provide a balanced effect in the forces imparted by the fan to the shaft.

While an illustrative form of the invention has been disclosed in considerable detail, it will be understood that various changesmay be made in the construction and arrangement of the several parts without departing from the general principles-and scopeof'the invention as'defined by the appended claims.

I claim:

1. '-In a lockstitch sewing machine a rotary hook having a rotary component including a hub, "a shaft to which said rotary component is secured, a' bearing for said shaft spaced a short distance from said rotary component, a fan secured to said shaft independently of said rotary component between said hub of said rotary component and said'bearing, said 'fan'consisting of ahubanda plurality of radially extending blades, andstationarymeans surrounding said fan arranged todire'ct'a stream of air toward said rotary component.

"2. -In a lockstitch"seWing machine a frame havme a work supporting base, *a bearing sleeve mounted in adepending portion of said base, 'a

shaft journaled in said bearing sleeve, a rotary hook having a rotary component including a hub secured to said shaft at a short distance from said bearing sleeve, and a fan secured directly to said shaft between said hub of said rotary c0m ponent-and said sleeve, said depending portion of said base being provided with at least one opening adjacent said bearing sleeve through which said fan is arranged to draw air along said sleeve and direct it against said rotary component.

3. In a lockstitch sewing machine a frame having a work supporting base, a bearing sleeve mounted in said base, a shaft journaled in said bearing sleeve, a rotary hook having a rotary component including a hub secured to said shaft at a short distance from said bearing sleeve, and a fan secured directly to said shaft between said hub of said rotary component and said sleeve, said frame having a portion extending longitudinally beyond the end of said sleeve and spaced from the axis thereof to provide a hood around said fan adapted to direct a stream of air toward said rotary component.

4. In a lockstitch sewing machine a frame having a work supporting base, a bearing sleeve mounted in said base, a shaft journaled in said bearing sleeve, a rotary hook having a rotary component including a hub secured to said shaft at a short distance from said bearing sleeve, and a fan secured directly to said shaft between said hub of said rotary component and said sleeve, said frame having openings therethrough around said sleeve and having a portion extending longitudinally beyond the end of said sleeve and spaced from the axis thereof to provide a hood around said fan adapted to direct a stream of air toward said rotary component.

NORMAN V. CHRISTENSEN.

REFERENCES CITE?) The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,180,756 Harding Nov. 21, 1939 

